TS-4720 eMMC

From Technologic Systems Manuals

This board includes an onboard 4GB eMMC disk. The datasheet for this Micron part can be accessed here. This disk is accessed very similar to an SD card and is also supported with the sdctl driver. This eMMC supports read and write speeds at approximately 10MB/s. The kernel provides access to the flash at /dev/nbd1 for the entire block device. The kernel also includes a module that will break this up into partitions. Our default software image contains 2 partitions:

Device Contents
/dev/nbd1 eMMC block device
/dev/nbd1p1 Kernel and initramfs
/dev/nbd1p2 Full Linux Root

Pre 11/2/2014 release TS-4720 eMMC by default uses Single card doublestore. To access the Linux partition of the SD card while booted to eMMC, you can use the mount command as expected:

mkdir /mnt/sd
mount /dev/nbd1p2 /mnt/sd

Post 11/2/2014 release TS-4720 eMMC uses Enhanced SLC mode eMMC, allowing for even greater reliability and longer lifespan. To access the Linux partition of the SD Card while using this eMMC, read the device partition table, and then mount as normal:

busybox blockdev --rereadpt /dev/nbd1
mkdir /mnt/sd
mount /dev/nbd1p2 /mnt/sd

A useful script for this device read activity has been included in the ts.subr definitions file for use within custom startup scripts:

# excpecting "source ts.subr" is already done
scan_lun <lun number>
mkdir /dev/sd
mount /dev/nbd1p2 /mnt/sd